Electromagnet assembly with interfitting parts



May 26, 1964 Filed March 13,

L. E. LAWRENCE 3,134,869 ELECTROMAGNET ASSEMBLY WITH INTERFITTING PARTS4 Sheets-Sheet l e: 1 M 3 v 165 72 INVENTOR Z5 LELAND E. LAWRENCE '524-7 how/2M ATTORNEY y 26, 1964 L. E. LAWRENCE 3,134,869

ELECTROMAGNET ASSEMBLY WITH INTERFITTING PARTS Filed March 13, 1962 4Sheets-Sheet 2 4-gl v f I 7 7 I 3 50 4-0 I 4- 4 in nu h will h i s5 19 i3 74 M g 6' 7 A 1 55 4 2 3|- 3 65 5 =Z4 /2 32 .I

73 lNVE OR 0 5 4a] M. LELAND E. WRENCE 20 Q 66 I 4 'i BY KM,

45/35,? ATTORNEY y 26, 1964 L. E. LAWRENCE 3,134,869

4 Sheets-Sheet 3 INVENTOR z'v-fi l 72 LELAND E. LAWRENCE BY /9 lo q 53 g38 ATTORNEY May 26. 1964 L. E. LAWRENCE 9 ELECTROMAGNET ASSEMBLY WITHINTERF'ITTING PARTS 4 Sheets-Sheet 4 Filed March 13, 1962 INVENTORLELAND E. LAWRENCE ATTORNEY United States Patent 3,134,869 7ELECTROMAGNET ASSEMBLY WITH INTERFITTING PARTS Leland E. Lawrence,Wauwatosa, Wis., assignor to Allen- Bradley Company, Milwaukee, Wis, acorporation of Wisconsin Filed Mar. 13, 1962, Ser. No. 179,362 17Claims. (Cl. 200-87) This invention relates to electromagnets forswitches and the like, and it more particularly resides in an improvedelectromagnet assembly with interfitted parts that contribute toimproved use and operation.

The electromagnet assembly of this invention includes a frame, a coiland magnetic yoke received in the'frame, a movable contact carryingactuator that is slidably mounted by the frame and carries a magneticarmature, and a protective cover. It is the general object of thisinvention to provide an electromagnet assembly of this type thatincludes a number of novel structural features which serve to improvethe operation of the assembly, reduce wear on the various elements,allow for economical and efficient manufacture, simplify assembly, andprevent assembling the various parts in improper orientations.

It is one of the specific objects of this invention to proyide a frameand actuator that have mating tapered surfaces to' prevent placing theactuator in the frame in any but its proper orientation.

It is another object of this invention to provide a coil that hasopenings to receive the yoke, the yoke and the coil openings beingprovided with mating fillet and cutout portions to prevent improperassembly.

It is another object of this invention to provide a coil that fitsthrough an opening in the protective cover and is held therein by aresilient holding means which holds the coil securely in place duringoperation of the electromagnet assembly to prevent the Wear and leadbreakage which might otherwise result from the hammering action of thearmature and which also allows for the cover, coil and yoke to besub-assembled and inserted into the frame as a unit during finalassembly.

It is another object of the invention to provide abutments on the coilthat aid in sub-assembling the coil, cover and yoke and that cooperatewith mating ledges in the frame to locate and hold the coil in properorientation and prevent improper assembly.

It is another object of the invention to provide mating beveled surfaceson the yoke and frame to prevent the yoke from being improperly insertedin the frame.

It is another object of the invention to provide a tapered key mountingfor the yoke in the frame to prevent improper assembly and to preventrocking or whipping of the yoke during operation of the electromagnet.

It is another object of this invention to provide an auxiliarycontactassembly for incorporation in a control circuit in which an auxiliarycontact housing is formed as an integral part of the protective cover ofthe electromagnet assembly and the lever foroperating the auxiliarycontacts, which is itself operatediby a crossbar carried by theactuator, is pivotally mounted in the housing with a maximum bearingsupportand is soformed as to prevent damage to the lever 'or auxiliarycontacts resulting from improper alignment of the lever and crossbarduring assembly.

Itis another object of this invention to provide a shim formed .of amaterial having natural lubricity between the 3,134,869 Patented May 26,1964 facing surfaces of the cover and actuator to prevent excessive wearof these and associated elements due to repeated operations of theactuator, which wear could otherwise cause deleterious accumulations ofdust or misalignment of the parts of the electromagnet.

It is another object of this invention to provide an armature that issecurely but resiliently mounted on the actuator and cooperates withribs formed in the frame and protective cover to prevent the armaturefrom being driven out of alignment with the actuator by dropping orother abuse of the assembly.

It is another object of this invention to provide an actuator that hasvisible markings thereon which may be viewed through cutout portions ofthe protective cover to indicate visually the position of the actuator.

It is another object of this invention to arrange the various taperedand beveled surfaces of the elements in such a manner as to providesufficient draft for die casting of the frame.

It is another ,object of this invention to provide an electromagnetassembly incorporating the foregoing features which can be efficientlyand economically manufactured.

Other objects and advantages will appear from the description to follow.In the description, reference is made to the accompanying drawings,forming a part hereof, in which by way of illustration and not oflimitation a specific embodiment of the invention is shown.

In the drawings:

FIG. 1 is a front view in elevation of an electromagnetic switchincluding an electromagnet assembly formed according to this invention,

FIG. 2 is a side view in elevation, with parts broken away and insection and other parts shown in dotted lines, of the switch of FIG. 1,

FIG. 3 is a fragmentary View in cross-section taken along the plane 3 3shown in FIG. 1,

' FIG. 4 is a fragmentary view in cross-section taken along the plane4-4 shown in FIG. 1,

FIG. 5 is a fragmentary view in along the plane 55 shown in FIG. 4, FIG.6 is a fragmentary view in cross-section taken along the plane 66 shownin FIG. 3,

FIG. 7 is a view in perspective of a sub-assembly of the switch of FIG.1- including the coil, yoke and protective cover,

FIG. 8 is a view in perspective of the actuator of the switch of FIG. 1,and

FIG. 9 is a view in perspective of the electromagnet frame and mountingplate of the switch of FIG. 1.

The electromagnetic switch shown in the drawings includes a sheet metalmounting plate 1 provided with a cross-section taken .set of threeapertures 2 for mounting upon apanel, or in an enclosure, as desired.The configuration of the plate 1 is most clearly shown in FIG. 9, and asviewed therein, one of the apertures 2 is an inverted keyhole slot atthe top and the others constitute a pair of round holes at the bottom. Ametal frame, indicated generally by the numeral 3, is mounted on theplate 1 by means of rivets 4, which are shown in FIGS. 2, 3 and 9. Theframe 3 is preferably formed of die-cast aluminum, and as previouslystated it is among the special advantages of this in vention that theframe 3 can be die cast so as to be given the configuration to bedescribed. Also, the frame 3 has heat transmitting properties as arediscussed in US. Letansasea ters Patent No. 2,903,537 which discloses aframe having some similarities to the frame of the present invention.

As seen most clearly in FIG. 9, the frame 3 is of rather complexconfiguration, and includes a centrally located rectangular coil socket5 that is provided in its upper wall with a channel shaped cutoutportion, or recess 6. The recess 6 is also shown, in section, in FIG. 3,and it imparts an irregular configuration to the coil socket, whenviewed from the front, to act as a guideway for orientation of partsduring assembly, as will hereinafter be discussed. Immediately above thecoil socket 5, the frame 3 extends outwardly to provide a vertical yokereceiving riser 7 that defines a yoke socket with an upwardly andforwardly inclined beveled upper edge 8. Such beveled edge forms anotherguide for correct orientation of parts during assembly, and gives anirregular configuration to the yoke socket. A pair of laterally spaced,

' forwardly extending yoke receiving arms 9 which determine the laterallimits of the yoke receiving riser 7, and hence partly define the yokesocket, are also disposed immediately above the coil socket 5. The arms9 are each provided with inwardly and forwardly opening keyway slots 10which, as can be seen in FIG. 4, are tapered so as to have a greatervertical dimension at their forward ends, whereby the taper presentsdivergent surfaces A horizontal mortise slot 23 extends through themidsection of the yoke 21, and a phenolic impregnated, laminated canvaskey piece 24 of a generally rectangular surface configuration extendsthrough the slot 23 to overhang on either side of the yoke 21. Theoverhanging ends of the key piece 24 are received in the keyways 10 ofthe arms 9, and as specifically shown in FIGS. 3 and 4 the key piece 24and slot 23 are both tapered, or divergent, to match the taper, ordivergency, of the keyways 10. Thus, the key piece 24 can be inserted inthe yoke slot 23 only when its narrower edge is in alignment with thenarrower end of the slot 23, which is at the rear end of the yoke 21.Also, the key piece 24 cannot be inserted in the keyways 10 unless itsnarrower edge is facing towards the rear of the device. Thus, the yoke21 and key piece 24 can be sub-assembled in only one orientation; andthis subassembly can be inserted into the frame 3 in only one way toprevent end-for-end reversal during assembly.

The divergent taper of the keyways 10 also aids in I die casting theframe 3 by providing sufficient draft.

for each slot 10. As seen most clearly in FIG. 6, the

outer, or side, surfaces 11 of the arms 9 are also divergent and taperinwardly from the rear to the front of the arms 9. The arms 9 are alsoprovided on their lower surfaces with coil locating ledges 12 and attheir forward ends with threaded screw receiving openings 13.

The frame 3 also includes at its lower corners a pair of forwardlyextending actuator receiving posts 14 that are generally trapezoidal incross section configuration. The posts 14 include inwardly and upwardlyfacing oblique surfaces 15 and inwardly facing vertical surfaces 16, andas seen in FIG. 5, the surfaces 16 are tapered outwardly from the rearof the posts 14 to diverge from one another. The posts 14 are preferablycut away on their outer side surfaces and on their bottom surfaces as at17 to provide electrical clearance for protective relays (not shown) oneither side of the frame and to provide cover locating surfaces formating engagement with a cover as will be hereinafter described.Similarly as the arms 9, the posts 14 also include in their forward endsthreaded screw receiving openings 18.

The frame 3 is further characterized by the inclusion of a set of fourforwardly facing, vertically disposed actuator guide surfaces 19 thatare located alongside the arms 9 and the posts 14. The two surfaces 19associated with the posts 14 lie to their immediate inside, so as tohave common boundaries with the surfaces 15 and 16, and extend upwardlyfor a short distance above the posts 14. The remaining two surfaces 19are immediately adjacent the outer sides of the arms 9 to form the baseof the arms at these points, and all of the surfaces 19 lie in a commonvertical plane. An armature restricting rib 20 is also shown in FIGS. 3,4 and 9 as a part of the frame 3, and it extends horizontally betweenthe posts 14. To complete the frame 3 a horizontal mounting ledgeextends across the top to receive a contact hood to be described.

Referring now to FIGS. 3 and 6, a generally U-shaped, laminated,magnetic yoke 21 is mounted between the arms 9 in an inverted position,so that its two legs 27 project downwardly. The rear surface of the yoke21 is adjacent the yoke receiving riser 7, and the upper rear edge 22 ofthe yoke 21 is beveled to mate with the beveled edge 8 of the riser 7.The beveled edges 22 and 8 must mate in order for the yoke 21 to beinserted fully into the frame 3, and it is therefore impossible tomistakenly reverse the yoke 21 end-for-end during assembly of theswitch, because of the irregular configuration of the yoke socket. Thus,when the magnet is assembled the magnetic yoke 21 is received in theyoke socket with definite orientation.

Further, the matching taper of the key piece '24 provides a moreadequate bearing area between the upper surface of the key piece 24 andupper side of the keyways 10 than would be present if an untapered keypiece were used in a tapered slot, thus helping to prevent rocking orwhipping of the key piece 24, and the yoke 21, when the yoke 21 isstruck during operation of the switch.

Referring now to FIGS. 3, 4, 6 and 7, there is shown a generallyrectangular coil indicated generally by the reference numeral 25. Thelengthwise dimension of the coil 25 extends in the fore and aftdirection, so that one end will be received within the coil socket 5 ofthe frame 3. This end of the coil 25 is that which is viewed in FIG. 7,and it is seen that the coil end will conform quite closely with thesocket 5, so that a fairly snug fit will be had which adequatelysupports the after end of the coil 25 in a fixed position. As is mostclearly shown in FIG. 3, the coil 25 has a pair of windings andsupporting and insulating plates, all encased in an insulating shellformed of an epoxy or other suitable resin, and

the central eye of each winding is open to define a pair of spaced coilopenings 26 which receive the magnetic members of the switch.

The downwardly extending legs 27 of the yoke 21 extend downwardly intothe coil openings 26 from the upper side of the coil 25, and as can beseen most clearly in FIG. 6, fillets 28 are provided along the left rearcorner of the rear coil opening 26 and along the left front corner ofthe front coil opening 26, which mate with cutout edges 29 formed ineach yoke leg 27 by provision of a side plate 30 for the yoke 21 that issomewhat shorter than its laminations. The cutout edges 29 and fillets28 must mate before the yoke legs 27 can be inserted into the coilopenings 26 and, therefore, it is impossible to sub-assemble the yoke 21and coil 25 in any but their one proper orientation.

As best seen in FIG. 7, the coil 25 is also provided with an integrallyformed boss 31 at the rear of its upper surface, and with a pair ofintegrally formed side bosses 32 also on its upper surface, butalongside the magnetic yoke 27 when it is assembled with the coil. Whenthe coil 25 is inserted into the frame 3, the boss 31 is received in therecess 6 of the coil socket 5, to thereby match the irregularity of thecoil socket configuration and to have the guideway presented by therecess 6 orientate the parts in assembly. Also, the rear edges of thebosses 32 abut against the ledges 12 formed in the arms 9. Theseengagements serve to locate and fix the coil 25 in proper position inthe frame 3, so that the coil 25 cannot be reversed, i.e. turned over,during assembly. In addition, the coil 25 cannot be reversed,end-for-end, since it has terminals 72 which must appear at the front.

As seen most clearly in FIGS. 3 and 6, the coil 25 is also provided atthe front of its upper surface with a resilient holding member '33 inthe form of a flat spring extending across thewidth of the coil "25 andprovided with a cutout portion in register with the front coil opening26.

The holding member 33 is formed .ofany suitable resilient -erally by thenumeral 36, seen most clearly as the principal element in theperspective views of FIG. 8, is slidably mounted, when the switch isfully assembled, in the frame 3 and includes a base portion 37, a pairof side members 38 and a crossbar portion 39. The actuator 36 ispreferably'formed of a sturdy insulating material such as a phenolformaldehyde molding compound which will provide bearing surfaces forthe actuator as it moves upward and downward in a guided movement.

When the actuator 36'is assembled with the frame 3 the base portion 37extends crosswise between the actuator receiving posts 14, as shown inFIG. 5, and the lower ends of the side members 38, Where-they merge withthe base portion 37, cross over the tops of the posts 14' and extendupwardly alongside the coil 25 and the outer faces of the arms 9. Thecrossbar portionj39 joins the upper ends of the side members '38 andextends across the upper face of the magnetic yoke 21.

During operation of the switch, the back faces ,of the side members 38slide along the slide surfaces 19 of the frame 3 in a verticalreciprocating motion, and at the lower ends of the side members 38 theactuator36 is provided with oblique surfaces 40 which engage with andmate the surfaces 15of the posts14 to limit downward movement of theactuator 36. The vertical outer side surfaces 41 which define thecrosswise ends of the base .portion37, and which are immediately belowthe oblique surfaces 40, are tapered. outwardly from the rear to thefront to match the taper of the surfaces 16 of the posts 14. Further,the inner. surfaces ofthe side members 38 .areprovided attheir upperends with inwardly tapered guide surfaces 42 which. mate withthe taperedsurfaces 11 of the arms -9. Since the surfaces 42and 11 and 41 and 16must mate before theactuator 36 can be inserted fully into the frame 3,it is impossible to reverse the actuator 36 face for-faceduringassembly.The tapered surfaces 16 and 11 are of further benefit in providingsufli- ..cient draft for die casting the frame 3, .and the surfaces 41and'42 are of benefit in providingdraft for molding the actuator 36.

Theforward surface of each side member 38 is provided with an indicatingsection 43. painted, or otherwise colored, soas to contrast distinctlywith the remainder of .the members 38. The contrasting indicatingsections 43 enable the position of the actuator 36 to be determinedvisually in a manner .tobe hereinafter described.

An upwardly opening, generally. U-shaped. laminated magnetic armature'44is mounted on thebase37 of the :actuator 36 by means of a pair of sideplates 73 having :sidewardly extending flanges 45 which are received in.aslot 46 inthe base '37. ,A flat insulating shim 47 formed .ofaflphenolic molding compound is placed below the flanges 45 and aresilient flat holding spring48 of any suitable material is interposedbetween the shim .47 and base .37. Although the spring-48 is resilient,it is'preferably quite strong to minimize any movement of the armature-44 with respect to the actuator36, while still providing suflicientresilience: to take upsome of the shock transmittedduringclosing'oropening of the switch.

The switch also includes aicaprlike front cover indicated generally bythe numeral 49and preferably molded of an insulating material such as aphenol formaldehyde mold- ..ing compoundysimilar to that usedforstheactuator .36.

The cover 49 at its lower corners is provided with inan actuatingposition.

'wardlyiextending rims 50 which mate with the cover 10- cating surfaces.17 of the actuator receiving posts 14 to locate and. hold the cover 49in position. Generally triangularcutout portions 51 are provided on eachside of the cover49-and are so located with respect to the indicatingsections 43 of the actuator 36 that the. indicating sections. 43 can beviewed through the cutout portions 51 only when the actuator 36 has beenmoved upwardly to Thus by looking through thecutout portions 51 from thefront of theswitch it is possible to determine whether the actuator 36has or has not moved to its actuating position.

The cover 49 is also provided with a generally rectangular aperture 52extending across its front facethrough which protrudes the forward endof the coil 25. presenting the terminals 72. The spring 33 is interposedbetween the upper front surface of the coil 25and the upper side of theaperture-52, .to hold the coil 25 securely in place with respect to thecover 49. This serves to hold the coil '25 firmly, but resiliently inplace during operation of the switch to prevent lead breakage and wearwhich might otherwise occur because of thehammering action of themagnetic elements. Also, since the coil 25-and cover 49 are held tightlytogether by means of the spring 33, it is possible to insert the yoke 21into the coil 25 and the coil 25 intothe cover 49 to create thesub-assembly shown in between the rear face of the cover 49 and thefront surfaces of the side members 38 of the actuator 36 to prevent thewear and resultant accumulation of dust which might otherwise occurbecause of the sliding action of these elements on one another duringthe operation of the switch. The provision of the shims 53 also servesto preventwear on other elements of the switch, which might resultshouldthe actuator 36 become misaligned after being worndown.

Four assembly screws 54 pass through the cover 49 and are received inthe threaded openings 13 and 18 of the arms 9 and posts 14,respectively, to hold the ,cover 49 in place on the frame 3. The screws54 are preferably plus threaded with the threaded portion being vof suchlength as to be to the rear of relatively tight fitting openings in theshims 53, whereby the threads on the screws 54 act as a retainer for theshims 53 to hold the shims 53 in place during assembly. Thus the shims53 and mounting screws 54 form a part of the sub-assembly of FIG. 7.Also, the openings in the cover .49 which receive the screws 54 arepreferably provided with severalthreads at their rear ends to act as aretainer for the screws 54 during assembly and to compens ate for thereduced diameter of the screw shaft, due

to the plus threading, thus locating the screws 54 with respect to thecover 49.

The cover 49 is also provided at its top center with an integrallyformed, box-like auxiliary contact enclosure '55. A pin .56 passestransversely through the enclosure 55 and is preferably formed of anacetal polymer, and is held in place in any desired manner. The pin 56pivotally mounts a short quill 57 that functions as an integral bearingportion of an auxiliary contact lever 58. .The auxiliary contact lever58 is preferably formed of nylon, since nylon can easily be injectionmolded to form the tube like quill portion 57, which serves to pro- FIG.3, is seated ,at oneend against the interior'wall of the enclosure 55,and works at itsopposite end against the lever 58 to urge the lever 58in a counterclockwise direction, as viewed in FIG. 3. At its forwardend, the lever 58 is provided with an opening 61 through which passes atransversely disposed, normally open bridging contact 62 that ispreferably formed of a resilient, electrically conductive metal withsuitable contact surfaces at both ends. A spring 63 seated against theupper wall of the opening 61 serves to urge the bridging contact 62against the lower wall of the opening 61. A pair of stationary contacts64 are also mounted within the enclosure 55, on opposite sides of thelever 58, and extend outwardly to present terminals 65 for connectioninto an auxiliary circuit. This auxiliary contact structure operates inthe usual manner, in that when the actuator 36 is raised the lever 58 iscaused to pivot in a clockwise direction, as seen in FIG. 3, thus movingthe bridging contact 62 against the bias force of the spring 60, intoclosed position with respect to the stationary contacts 64. Theenclosure 55 may also mount a second set of stationary contacts, notshown, above the bridging contact 62 in a position that they are engagedby the contact 62 when in its raised position of FIG. 3. In this fashionnormally closed contacts may be provided as well as normally opencontacts, and they can be advantageously used in reversing switchapplications and the like.

The lever 58 is arranged to have a slight overtravel, and this in efiectcauses the bridging contact 62 to be lifted, against the spring 63, offthe bottom wall of the opening 61 after initial contact, the spring 63thereafter serving to hold the bridging contact 62 in closed position.The lever 58 extends downwardly below the opening 61 to provide a stop75 engageable with the bottom Wall of the enclosure 55 to limit thepivotal movement of the lever 58. This prevents any damage which mightbe caused to the lever 58 or the bridging contact 62 should the lever 58be pivoted too far during assembly of the switch, as when it isattempted during assembly to lift the lever 58 onto the upper surface ofthe crossbar 39 while the actuator 36 is in its upper position. Also,the rear end 74 of the lever 58 is quite blunt to prevent it fromsliding under the crossbar 39 if the actuator 36 is in a slightly raisedposition during assembly.

As seen in FIGS. 3 and 4, the cover 49 is also provided with ahorizontally extending, integrally formed rib 66 which is alongside theforward end of the armature 44 with a slight clearance therebetween. Therib 66 and the rib 20 in the frame 3 serve to prevent dislocation of thearmature 44 should the switch be dropped or otherwise abused.

The crossbar 39 of the actuator 36 forms a support for movable contactcarrying cages 67 which carry movable contacts 68 and extend upwardlyinto an arc enclosure indicated generally at 69. Stationary contacts 70,seen in FIG. 2, are mounted in the enclosure 69 and terminals 71 areprovided for connection into a line circuit. No attempt is made hereinto describe the contact assembly of the switch with any particulardegree of specificity, since it will be well understood that any numberof contact assemblies could be used and that the invention hereinresides essentially in the electro magnetic elements hereinbeforedescribed. The operation of the switch of this invention will also beunderstood without being described in any great detail, it beingsuflicient to note that when the coil 25 is energized the armature 44 isattracted toward the yoke 21 whereby the actuator 36 is moved upwardlyto bring the movable contacts 68 into closed position with thestationary contacts 69. Upon deenergization of the coil 25 the actuator36 falls downwardly of its own weight to break the circuit.

The electromagnet of this invention has demonstrated excellentmechanical life characteristics, with operations of small size switches,for example, running upward to 40 million and above. The interfittingparts, in which the actuator is guided by bearing surfaces ofsubstantial area that exhibit little wear, and in which the coil is heldsecurely for minimal vibration, have contributed to the life obtained.Further, the mounting of the magnetic yoke with a key piece extendingentirely through its central portion and resting with a small clearancein the adjacent arms has contributed to the results obtained. When thearmature strikes the magnetic yoke shock is absorbed in the frame andthe phenolic key piece and in the slight motion of the yoke provided bythe small clearance between it and the key piece and between the keypiece and frame. The use of subassembly of FIG. 7 can be of advantage inassembly of the switch. The sub-assembly of FIG. 7 is self-sustaining byreason of the retaining spring 33, and in assembling the device in thismanner the actuator assembly of FIG. 8 is first placed in the frame 3,from the front, and then with the actuator in its lower position, thesub-assembly of FIG. 7 is brought into the frame 3, again from thefront, and the mounting bolts 54 are secured. In order for thesub-assembly to be inserted, the actuator 36 must be in its lower ordown position, thus preventing damage to the lever 58 by engagement withthe edge or lower surface of the crossbar 39. The parts thus interengageWithout any complication, and the possibility of mismatching any of theelements is precluded. To complete assembly of the switch the front hoodportion 69 is mounted in place. If desired, however, the switch can alsobe readily assembled without first creating the subassembly of FIG. 7since, as hereinbefore discussed, the various parts and therelationships between them prevent improper assembly even when the partsare inserted individually.

I claim:

1. In an electromagnet the combination comprising: a base frame having apair of forwardly projecting arms extending therefrom that are laterallyspaced with respect to one another to present facing inner surfaces,said arms being provided with keyway slots that open along said facinginner surfaces and at the outer ends of the arms and which havedivergent surfaces; said frame also including a yoke socket that isbetween said arms and is of an irregular configuration; a magnetic yokehaving an after end received in and matching the.

configuration of said yoke socket and a keypiece slot extendingtherethrough, said keypiece slot having divergent surfaces matchingthose of said keyway slots and aligned with said keyway slots when saidyoke is received in said yoke socket; a keypiece extending through thekeypiece slot and outwardly on either side of the yoke to be received insaid keyway slots, said keypiece having divergent surfaces matching saidkeyway and keypiece slots; an operating coil mounted on said frame; anda. magnetic armature in facing relation to said yoke for operationtherewith in response to said coil.

2. In an electromagnet the combination comprising: a frame having a coilsocket with a forwardly and rearwardly extending guideway that providesan irregular configuration for the socket, and a pair of spaced armsextending forwardly from points adjacent the coil socket that areprovided on their lower surfaces adjacent the coil socket with forwardlyfacing coil locating ledges; and a coil having an after end with aprojection mating said guideway which is received in and matches theconfiguration of the coil socket and which coil has further projectionsextending therefrom that are engageable with the coil locating ledges,whereby the coil may only be inserted with desired orientation withrespect to said frame.

3. In an electromagnet the combination comprising: a frame having a coilsocket with a guideway that imparts an irregular configuration for thesocket; a pair of laterally spaced arms extending forwardly from abovethe coil socket which have facing keyway slots, and a yoke socketlocated between said arms and above said coil socket which has a guidethat imparts an irregular configuration to the yoke socket; a coilhaving an after end received in and matching the configuration of thecoil socket guidway whereby it may only be inserted in the coilsocketwith the proper side facing upwardly, said coil having a pair ofopenings with one to the front of the other and wherein at least one hasa yoke receiving guideway; a U-shaped yoke with ends thereof insertablein said coil openings with one yoke end matching said yoke receivingguideway for receipt of said yoke in the coil openings only upon matingthe guideway and matching yoke end, and the after'end of the yoke beingof an irregular configuration that matches said guide of said yokesocket in said frame for receipt of said yoke in the yoke socket onlyupon matching said irregular yoke end with said guide, said yoke alsohaving a keypiece slot extending therethrough which aligns with saidkeyway slots; and a keypiece extending through said keypiece slot andoutwardly on either side of the yoke to be received in said keywayslots.

4. In an electromagnet the combination comprising: a frame having a coilsocket with a recessformed in one side thereof, a pair of spaced armsextending forwardly from above the coil socket, said arms having facingkeyway slots that open along the facing inner surfaces and at theforward ends of the arms with the upper and lower surfaces of the slotsbeing divergent from rear to front and coil locating ledges formed ontheir lower surfaces, and a 'yoke socket between the arms with anoblique orientating surface along one edge thereof; a coil having anafter end that fits within the coil socket and has a raised boss thereonthat is received in the recess of the coil socket, a pair of openingsextending vertically therethrough that are provided with a fillet alongat least a portion of one edge, and a pair of raised bosses alongsidethe openings that are engageable with the coil locating ledges; amagnetic yoke the after end of which is received inthe yoke socket andis provided with an oblique surface matching the orientating surfacethereof, said, yoke having a pair of downwardly extending legs receivedin the coil openings and provided with cutout portions matching thefillets in the openings and a keypiece slot extending transverselytherethrough the upper and lower surfaces of which are divergent fromrear to front; and a keypiece extending through the keypiece slot oftheyoke, and outwardly on either side thereof to be received in thekeyway slots of the arms, the upper and lower surfaces of the. keypiecebeing divergent from rear to front to match the divergent surfaces ofthe keyway and keypiece slots. t

5. In an electromagnet the combination comprising: a coil havinga pairof spaced irregular openings therethrough; a yoke having a pair ofextendinglegs received in and. matching the irregular coil openings; acover having an opening through which an end of the coil is received;and a resilient holding member interposed between the coil and cover toresiliently hold the same against relative movement.

6. In .an electromagnet the combination comprising; a magnetic yokehavinga pair of extending legs atleast one of which. is provided, with acutout edge; a coil having spacedopenings to receive the legs of theyoke, at least 'one of said openings being provided with a filletcorresponding to the. cutout edge of a leg, said fillet being positionedto receive said yoke only upon orientation of said yoke with the cutoutedge of the yoke in position match ing thefillet, to assemble. the yoke,with the coil in proper orientation, said coil also having a pair ofraised bosses lying alongside theopenings; a cover having anopening forreceiving an end of the coil therethrough, said bosses beingengageable'with the cover toilimit movement ofthe coil" through theopening; and a resilient holding member carried by the coil; andinterposed between the coil and cover to resiliently hold the coil andcover against relative movement. V V

7. In an electromagnet the combination comprising:

a frame having a coil socket of an irregular configuration, a pair ofspaced arms extending forwardly from above the coil socket having facingkeyway slots with divergent surfaces, the outer surfaces of the armsbeing divergent, a yoke socket between the arms that has an irregular,configuration, and a pair of spaced posts extending forwardly from belowthe coil socket having divergent surfaces; a coil having an after endthat fits Within and matches the configuration of the coil socket andhaving an irregular opening extending vertically therethrough; amagnetic yoke the after end of which is received in and matches theconfiguration of the yoke socket and having a downwardly extending legreceived in and matching the coil opening and having a divergentkeypiece slot extending transversely therethrough; a keypiece extendingthrough the keypiece slot of the yoke and outwardly on either sidethereof to be received in the keyway slots of the arms, the surfaces of.the keypiece being divergent to match the divergent surfaces of thekeyway and keypiece slots; and a vertically reciprocable armaturecarrying actuator having divergent surfaces matching and guidinglyengageable with the divergent surfaces of the arms and posts.

8. In an electromagnet the combination comprising: a frame having a coilsocket of an irregular configuration, a pair of spaced arms extendingforwardly from above the coil socket having facing keyway slots withdivergent surfaces, the outer surfaces of the arms being divergent, andthe lower surfaces of the arms being provided with coil locating ledges,a yoke socket of an irregular configuration between the arms, and a pairof spaced posts extending forwardly from below the coil socket havingfacing inner surfaces that are divergent and inwardly and upwardlyfacing actuator blocking surfaces and having cover locating surfaces; acoil having an after end that fits within and matches the coil socketand having an irregular opening extending vertically therethrough andhaving a pair of projections on its upper surface that are engageablewith the coil locating ledges; a magnetic yoke the after end of which isreceived in and matches the yoke socket and having a downwardlyextending leg received in and matching the coil opening and having akeypiece slot extending transversely therethrough that has divergentsurfaces; a keypiece extending through the keypiece slot of the yoke andoutwardly on either side thereof to be received in the keyway slots ofthe arms, the surfaces of the key piece being divergent to match thedivergent surfaces of the keyway and keypiece slots; a verticallyreciprocable actuator having side members slidably supported by theframe, the facing inner surfaces of the side members being divergent tomatch and guidably engage the outer surfaces of the arms, a crossbarportion extending horizontally between the upper ends of the sidemembers above the arms and a base extending horizontally between thelower ends of the side members, the outer surfaces of the base beingdivergent to match the divergent surfaces of the posts, the actuatorbeing provided at the outer surfaces of the junctures of the sidemembers and base with surfaces matching the blocking surfaces of theposts to limit downward movement of the actuator; an armature mounted onthe base of the actuator; a cover releasably secured to the forward endsof the posts and arms extending rearwardly to rest against the cover 10-cating surfaces of the posts and serving to guide the actuator in itsvertical movement, said cover having an opening therethrough whichreceives the forward end of the coil; and a resilient holding memberinterposed be tween the coil and cover to resiliently hold the sameagainst relative movement.

9. The combination of claim 8 wherein the forward surfaces of the sidemembers are provided with visible markings and the cover is providedwith cutout portions through which the markings can be viewed.

10. The combination of claim 8 wherein thetcover includes an auxiliary.contact housing and there is provided an auxiliary contact lever that ispivotally mounted intermediate its ends in the housing and has a bluntafter end that rests upon the crossbar portion of the actuator and stopsformed at its forward end to limit its pivotal motion in the housing.

11. The combination of claim 8 in which the frame and cover are providedwith ribs to limit forward and backward movement of the armature.

12. In an electromagnet the combination comprising: a frame having acoil socket with a recess formed in one side thereof, a pair of spacedarms extending forwardly from above the coil socket having facing keywayslots that open along the facing inner surfaces and at the forward endsof the arms, the upper and lower surfaces of the keyway slots beingdivergent from rear to front, the outer surfaces of the arms beingconvergent from rear to front and the lower surfaces of'the arms beingprovided with coil locating ledges, a yoke socket shelf between the armswith an oblique orientating surface along one edge thereof, a pair ofspaced posts extending forwardly from below the coil socket havingfacing inner surfaces that are divergent from rear to front and inwardlyand upwardly facing oblique actuator limiting surfaces and having coverlocating surfaces on their lower and outer surfaces, and actuator guidesurfaces extending vertically from outside the arms to inside the posts;a coil having an after end that fits within the coil socket and has araised boss thereon that is received in the recess of the coil socketand having an opening extending vertically therethrough that is providedwith a fillet along at least a portion of one edge and having a pair ofspaced raised bosses on its upper surface the rear surfaces of whichrest against the coil locating ledges; a magnetic yoke the after end ofwhich is received against the yoke receiving shelf and is provided withan oblique surface matching the orientating surface thereof and having adownwardly extending leg received in the coil opening with a cutoutportion matching the fillet in the opening and having a keypiece slotextending transversely therethrough the upper and lower surfaces ofwhich are divergent from rear to front; a keypiece extending through thekeypiece slot of theyoke and outwardly on either side thereof to bereceived in the keyway slots of the arms the upper and lower surfaces ofthe keypiece being divergent from rear to front to match the divergentsurfaces of the keyway and keypiece slots; a vertically reciprocallymovable actuator having side members guidably engageable by the guidesurfaces of the frame, the facing inner surfaces of the side membersbeing divergent to match the outer surfaces of the arms, a cross barportion extending horizontally between the upper ends of the sidemembers above the arms, and a base extending horizontally between thelower ends of the side members, the outer surface of the base beingdivergent to match the divergent surfaces of the posts, the actuatorbeing provided at the outer surfaces of the junctures of the sidemembers and base with oblique surfaces matching the oblique surfaces ofthe posts; an armature mounted on the base of the actuator and having anupwardly extending leg received in the coil opening; a cover releasablysecured to the forward ends of the posts and arms and extendingrearwardly to rest against the cover locating surfaces of the posts andserving to guide the actuator in its vertical movement, said coverhaving an opening therethrough which receives the forward end of thecoil; and a resilient holding member carried by the coil and interposedbetween the coil and cover to resiliently hold the same against relativemovement.

13. In an electromagnet having a base frame, a coil and magnetic yoke inmounted relation to said frame, and a magnetic armature cooperativelyrelated with said coil and magnetic yoke, the combination comprising: anactuator reciprocably movable alongside said frame by said armaturewhich includes a cross bar portion; a cover to the front of said baseframe that is fastenable there to and which includes a contact hood atthe top front thereof; contacts within said contact hood; and a contactactuator mounted by the cover extending from within said contact hood tothe rear thereof to overhang said actuator crossbar in the path oftravel of the crossbar, the portion of said contact actuator in the pathof travel of said crossbar being thickened to strike said crossbar whenthe crossbar is in a raised position during mounting of the cover, tothereby preclude insertion of the contact actuator beneath the crossbar.

14. In an electromagnet an assembly of parts comprising a coil with amolded body having a pair of openings as viewed from the top, with oneopening toward the coil front and the other toward the coil rear; amagnetic yoke of inverted U-shape in which each depending end of theyoke fits within a coil opening and the yoke sits astride the coil andis carried thereby; a cover that receives the forward end of said coiland the forward end of said yoke; and a keypiece extending transverselythrough said yoke with ends that emerge from and overhang beyond thesides of said yoke; said coil, cover, yoke and keypiece constituting asub-assembly of the electromagnet; the assembly of the electromagnetfurther comprising: a base having a coil socket that receives the afterend of said coil, a pair of forwardly projecting arms that are abovesaid coil socket and laterally spaced with a yoke socket therebetween,and that have slots to receive said keypiece for mounting the yoke insaid yoke socket; a pair of laterally spaced posts beneath said coilsocket which also project forwardly; a movable actuator having anarmature mounting portion beneath said coil and between said posts andside arms that pass alongside said forwardly extending arms, and aU-shaped magnetic armature mounted by said actuator with ends alignedwith said coil openings for entry from beneath; said actuator andarmature being mountable together on said base, and said pre-assembly ofcoil, yoke, cover and keypiece then being slidable into the assemblywith said cover mating against the forward ends of said arms and posts.

15. The electromagnet of claim 14 in which said actuator has a crosspiece that connects between said side arms and extends above saidmagnetic yoke; and further having a contact assembly carried by saidcover which includes an operating arm extending into the path of travelof said actuator cross piece.

16. The electromagnet of claim 14 in which said cover has side portionsthat are to the front of said actuator side arms, such side portionshaving cut outs to make said side arms visible from the front, and saidside arms having marking indicia for movement into and out of alignmentwith said cut outs.

17. In an electromagnet the assembly of a coil having a molded body thatpresents a hard, non-deformable exterior with a pair of openings asviewed from the top, one opening being toward the coil front and theother toward the coil rear, and said coil having terminals at itsforward end; a magnetic yoke of inverted U-shape with each depending endof the yoke fitting within a coil opening and the yoke sitting astridethe coil a cover fitting snugly over the forward end of said coil andhaving an opening through which said coil terminals protrude, said coveralso receiving the forward end of said yoke and extending laterally fromthe sides and the bottom of said coil; and a keypiece extendingtransversely through said yoke with ends that emerge from and overhangbeyond the sides of said yoke; said coil, cover, yoke and keypiececomprising a subassembly with firm fits between parts; the assembly ofthe electromagnet further comprising: a base having a coil socket thatreceives the after end of said coil, a pair of forwardly projecting armsthat are above said coil socket and laterally spaced to receive saidyoke therebetween and having slots to receive said keypiece for mountingand sustaining the weight of the yoke, and a pair of posts beneath saidcoil socket which also project forwardly and are laterally spaced;

a movable actuator having an armature mounting portion beneath said coiland between said posts and extending upwardly over the posts and mergingwith side arms that pass alongside said forwardly extending arms forguided vertical movement; and a U-shaped magnetic armature mounted bysaid actuator with ends aligned with said coil openings for entry frombeneath; said actuator and armature being mountable together on saidbase and said pre-assembly of coil, yoke, cover and keypiece then beingslidable into the assembly with said margins of said cover matingagainst the forward ends of said arms and posts and closing over thefront of said actuator and armature.

References Cited in the file of this patent UNITED STATES PATENTS Besaget al. Aug, 28, White Oct. 7, Lawrence Sept. 8, Burch Feb. 9, JelleyJuly 25, Furnas et a1. May 15, Kruzic Oct. 23,

FOREIGN PATENTS Germany June 11,

1. IN AN ELONGATED THE COMBINATION COMPRISING: A BASE FRAME HAVING APAIR OF FORWARDLY PROJECTING ARMS EXTENDING THEREFROM THAT ARE LATERALLYSPACED WITH RESPECT TO ONE ANOTHER TO PRESENT FACING INNER SURFACES,SAID ARMS BEING PROVIDED WITH KEYWAY SLOTS THAT OPEN ALONG SAID FACINGINNER SURFACES AND AT THE OUTER ENDS OF THE ARMS AND WHICH HAVEDIVERGENT SURFACES; SAID FRAME ALSO INCLUDING A YOKE SOCKET THAT ISBETWEEN SAID ARMS AND IS OF AN IRREGULAR CONFIGURATION; A MAGNETIC YOKEHAVING AN AFTER END RECEIVED IN AND MATCHING THE CONFIGURATION OF SAIDYOKE SOCKET AND A KEYPIECE SLOT EXTENDING THERETHROUGH, SAID KEYPIECESLOT HAVING DIVERGENT SURFACES MATCHING THOSE OF SAID KEYWAY SLOTS ANDALIGNED WITH SAID KEYWAY SLOTS WHEN SAID YOKE IS RECEIVED IN SAID YOKESOCKET; A KEYPIECE EXTENDING THROUGH THE KEYPIECE SLOT AND OUTWARDLY ONEITHER SIDE OF THE YOKE TO BE RECEIVED IN SAID KEYWAY SLOTS, SAIDKEYPIECE HAVING DIVERGENT SURFACES MATCHING SAID KEYWAY AND KEYPIECESLOTS; AN OPERATING COIL MOUNTED ON SAID FRAME; AND A MAGNETIC ARMATUREIN FACING RELATION TO SAID YOKE FOR OPERATION THEREWITH IN RESPONSE TOSAID COIL.